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Chapter 6:Linux Virtual Server Overview
6.5.2 Firewall Marks
Firewall marks are an easy and efficient way to a group ports used for a protocol or group of related
protocols. For instance, if one is running an e-commerce site, firewall marks can be used to bundle
HTTP connections on port 80 and secure, HTTPS connections on port 443. By assigning the same fire-
wall mark to the virtual server for each protocol, state information for the transaction can be preserved
because the LVS router will route all requests to the same real server after a connection is opened.
Because of its efficiency and ease-of-use, administrators of LVS clusters should use firewall marks
instead of persistence whenever possible for grouping connections. However, administrators should
still add persistence to the virtual servers in conjunction with firewall marks to ensure the clients are
reconnected to the same server for an adequate period of time.
6.6 LVS Cluster — A Block Diagram
LVS routers use a collection of programs to monitor cluster members and cluster services. Figure 6–4,
Components of a Running LVS Cluster, illustrates how these various programs on both the active and
backup LVS routers work together to manage the cluster.
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